docs: def delete_cookie(self, key, path='/', domain=None):
          """Delete a cookie.  Fails silently if key doesn't exist.
  
          :param key: the key (name) of the cookie to be deleted.
          :param path: if the cookie that should be deleted was limited to a
                       path, the path has to be defined here.
          :param domain: if the cookie that should be deleted was limited to a
                         domain, that domain has to be defined here.
          """
          self.set_cookie(key, expires=0, max_age=0, path=path, domain=domain)